Reflux ratio control for fractionating columns



-2 1940- A. E. ROBERTSON REFLUX RATIO CONTROL FOR FRACTIONATING COLUMNS Filed Sept. 50, 1938 2 Sheets-Shea t l Oct. 22, 1940. V A RQBERTSQN 2,218,624

REFLUX RATIO CONTROL IFOR FRACTIONATING oLuMNs Filed Sept. 50, 1958 r 2 Sheets-Sheet 2 co; UM/V FA C ((5 .SEcT/ON CO N-DENJER Patented Oct. 22, 1940 UNITED STATES REFLUX RATIO CONTROL FOR FRACTION- ATING COLUMNS Anthony E. Robertson, New York, N. Y, assignor to Standard Oil Development Company, a corporation of Delaware Application September 30, 1938, Serial No. 232,493

,10 Claims.

This invention relates to a system for the operation of a fractionation column. More specifically it relates to a system for regulating the withdrawal of condensate from such a column, or for controlling the reflux ratio in the column. The invention is particularly adapted for use when the distillation rate is not constant and when the process is carried out at less than atmospheric pressure.

When it is necessary to operate a fractionation column under conditions in which the distillation rate is not constant, a problem in accurate reflux control is created which requires that the withdrawal of condensate from the column be so regulated as to maintain a substantially constant reflux ratio. Ordinarily, the solution is accomplished by withdrawing condensate intermittently to such extent that over a definite period of time, the desired reflux ratio is achieved. To do this it has been customary to provide valves in the product recovery lines or weir boxes and the like within the column, any of which may be either manually or auto: matically operated. Such arrangements, however, are usually awkward and when openings through the column walls are required, involve special stufling boxes and other expedients any of which are liable to leakage. When operating under reduced pressures with such devices, it is difiicult to properly maintain the pressure conditions at a constant value. By means of the invention now set forth, it is possible to avoid the complicated arrangements of previous apparatus and to overcome the deficiencies inherent therein.

The advantageous features of the invention as set forth above and as further disclosed herein may be fully understood from the following specification when read in conjunction with the accompanying drawings, in which:

Fig. 1 shows diagrammatically, in section, one arrangement of parts contemplated;

Fig. 2 shows a similar view of an alternative system; and v Fig. 3 illustrates another form of the system disclosed.

As shown in Fig. 1 the apparatus comprises fractionating a column! having a condenser 2 and a packed section 3. A product recovery line 4 is disposed in theupper portion of the column I to receive a stream of condensate from the condenser 2. In the preferred form, the line 4 is provided with a trap 5 and an upwardly opening funnel-shaped inlet portion 6. In order to interrupt the withdrawal of condensate and to provide for reflux in the column I, a movable bafile means is disposed above the inlet portion 6 of the line 4. As shown, the means comprises a spring member 1, secured to one wall of the column, as at 8, and having a bafile or shelf portion 9 at its upper end extending toward the inlet 6, and providing a bafile for said inlet. The baflle 9 preferably provides an inclined surface to lead condensate away from the inlet, returning the condensate as reflux to the column.

The spring member 1 also carries an armature [0 which is adapted to respond to energy changes in the electromagnet Il disposed, in this instance, outside the column. Activation of the electromagnet ll attracts the armature ID with a force suflicient to bend the spring member I and cause the baflle 9 to be withdrawn from above the inlet 6 to the line 4. Obviously the arrangement of parts as disclosed may be readily altered to provide for an inlet 6 which is normally uncovered and in which activation of the 'electromagnet operates to move the bafile over the inlet as required, In either case, the bafile 9 is returned to its normal position by the action of spring I. Timing mechanisms, or other automatic control means, not shown, may be employed to interrupt or induce activation of the electromagnet.

In Fig. 2, there is illustrated an alternate construction, which is particularly adapted for use when the tower is constructed of a magnetic material. In the arrangement shown, the spring member I of Fig. 1 is replaced by a substantially rigid arm I2, having a baflle or shelf portion l3 at its upper end, and pivotally mounted in the tower by the lower end as at l4. Movement of the arm I2 is accomplished by means of electromagnets H and Ila. mounted in opposed relation within the tower, and acting upon armatures l0 and Ma disposed on opposite sides of the pivoted arm l2. Wires [5, .l5a, l6 and Ilia, connected to the respective electromagnets H and Ila, are passed through sealed openings in the tower walls and are suitably protected therein. The action of the apparatus thus described is substantially similar to that of Fig. 1, except that movement of the arm and bafile members is entirely dependent upon electromagnetic means.

In Fig. 3, another form of apparatus, according to this invention, is shown. The tower l, in this instance, is provided with a side chamber ll disposed at substantially the level of the inlet 6. The chamber I1 is not intended to be in free communication with the interior of the tower', but it is not necessarily vapor tight. The electromagnetic means I8, which is disposed in the chamber I1, is preferably of the solenoid type, and has a core member [9 which extends outwardly from the chamber, through an opening 20 in the tower wall, into the upper portion of the tower l. A baflie member 2| is secured to the outer end of the core member [8 and, under action of the solenoid, may be moved laterally of the tower between the condenser 2 and the inlet 6. An electric current is supplied to the solenoid l8 by means of wires 22 and 23 which pass through sealed openings in a wall of the chamber H.

In operation, a certain desired reflux ratio having been decided upon for the system, the means for activating'the electromagnet is suitably adjusted to provide the required intervals of reflux to the column and of product withdrawal therefrom. Distillation and fractionation is then begun. Assuming the use of a conventional timing mechanism to alternately make and break the circuit by which the magnet is energized, the armature will in like manner be drawn toward the column wall by the magnetic force, and moved away by the action of the spring to which the armature is secured. In this fashion, the baffle normally disposed over the inlet of the product recoveryline will, in repeated movements, uncover and recover the inlet for such periods of time as have previously been determined as adequate to obtain the desired results.

It should be apparent, that the foregoing description of the system and its method of operation is set forth for the purpose of illustration, and that various changes and modifications will be apparent to those versed in the art without departing from the inventive concept as set forth in the appended claims.

I claim:

1. A system for the fractionation of vaporizable liquids comprising in combination with a tower having a vapor space in the upper portion,

- a means for condensing vapors, returning condensate in a stream to the tower, a conduit, for withdrawingcondensate as a product, extending into said tower and opening upward within said vapor space to receive the stream, bafiie means for the open end of said conduit, movable with respect thereto from a position intercepting the stream to a position clear of the stream and return, and electromagnetic means for effecting said movement of the baflie.

2. A system for the fractionation of vaporizable liquids comprising in combination with a tower, a means for condensing vapors returning condensate to the tower, a conduit extending into the tower for withdrawing said condensate as a product, a baffle disposed within said tower and movable to shield the open end of said conduit, diverting the condensate therefrom as reflux to the tower, and means for moving said bafile by the action of an electromagnetic force away from the conduit to permit the condensate to flow into the conduit.

3. A system for the fractionation of vaporizable liquids comprising in combination with a tower, a means for condensing vapors returning condensate to the tower, a conduit extending into the tower for withdrawing said condensate as a product, a movable baflie shielding the open end of said conduit, diverting condensate therefrom as a reflux to the tower, an armature connected to said bafile, and means for moving said. baflle away from the conduit by the action of an electromagnetic force on the armature.

4. A system for the fractionation of vaporizable liquids comprising in combination with a tower, a means for condensing vapors returning condensate to the tower, a conduit extending into said tower for withdrawing condensate as a product, a movable baflie shielding the open end of said conduit, diverting condensate therefrom as a reflux to the tower, electromagnetic means for moving said baflie away from the conduit, and spring means for repositioning the bafiie to shield the open end of said conduit.

5. A system for the fractionation of vaporizable liquids comprising in combination with a tower, a means for condensing vapors returning condensate to the tower, a conduit extending into said tower for withdrawing condensate as a product, spring means secured in said tower adjacent the conduit, a shield for the open end of said conduit, to divert condensate therefrom as reflux to the tower, said shield supported by said spring means, an armature on said spring means, and an electromagnet acting upon said armature to move said shield against the resistance of said spring means.

6. A system for the fractionation of vaporizable liquids comprising in combination with a tower, having a vapor space in the upper portion, a means for condensing vapors, returning condensate in a stream to the tower; a conduit for withdrawing the stream of condensate as a product, extending into said tower, and opening upwardly within said vapor space; bafile means for the open end of said conduit movable with respect thereto laterally of the tower; an arm movably supporting said baffle, pivotally mounted within the tower to move the baflie from a position intercepting the stream to a position clear of the stream; armature members secured to said arm in opposed relation at a point intermediate the ends, and extending laterally toward the tower walls, electromagnets secured to said walls substantially concentric with said armatures; and means for energizing the electromagnets in sequence whereby the above movements of the bafiie are eifected.

7. A system for the fractionation of vaporiza- -b1e liquids comprising in combination with a tower, having a vapor space in the upper portion, a means for condensing vapors, returning condensate in a stream to the tower, a conduit for withdrawing the stream of condensate as a product, extending into saidtower and opening upward within said vapor space, a side chamber secured to the outer face of one wall of the tower substantially at the level of the open conduit end, a solenoid in said chamber, a core member in said solenoid extending through an opening in the wall of the tower, baflle means carried by said core member, and disposed intermediate the condensing means and the open conduit end, said core member andbafiie means being movable with respect to said open conduit end by the action of the solenoid from a position intercepting the-stream to a position clear of the stream and return.

8. A system according to claim 1 in which the means for moving said baiile by the action of an electromagnetic force consists of an electro-' magnet disposed within the tower and energized from a source of electric current outside the tower, and an armature connected with said bafile and disposed within the field of said electromagnet.

9. A system according to claim 1 in which the means for moving said baffle by the action of an electromagnetic force, consists of an electromagnet disposed outside the tower, means for energizing said electromagnet, and an armature connected with said baflle and disposed within the field of said electromagnet.

10. A system according to claim 1 in which the means for moving said bafiie by the action of an electromagnetic force, consists of a solenoid within the tower, and energized from a source of electric current outside the tower, in which 5 the magnetic core is connected to said baffle.

ANTHONY E. ROBERTSON. 

